International Science Community Association Research Journal of Forensic Sciences 13 1 2025 01 29 DNA profiling resolves the Paternity dispute reporting an Ambiguous Mutation at Autosomal STR CSF1PO 1 10 EN Sharma Rakesh Roshan 1 Biology/DNA Division, Regional Forensic Science Laboratory, Ajmer, Rajasthan, India > Research Paper 2023 11 13 2025 01 29 DNA profiling is the universally accepted gold standard technique for the human identification purpose in forensics. Paternity testing plays a crucial role in determining biological relationships and resolving legal and personal disputes. CSF1PO is the CODIS validated core locus. Reported allelic range for this short tandem repeat (STR) locus is from 6 to 15 repeats of the tetra-nucleotide AGAT. This paper explores a challenging case of sexual assault with an add-on paternity dispute. Reference samples of putative father, mother and child were processed for DNA profiling adopting standard protocols using the Powerplex® Fusion 6C system kit. Genotype of the child exhibits a gain of one repeat at the locus CSF1PO and exhibited 12/13 configuration, while both parents possess identically homozygous genotype of 12/12 at the same locus. Despite considering the existence of a mutation, the source of this additional repeat remains unidentified in the DNA profiling, limiting conclusive determination of the source of this ambiguous mutation whether it is the mother or the putative father. Other alternative PCR kits were used to analyze additional STR loci and to confirm a mutation at the locus CSF1PO. The existence of mutations was considered in the light of well established "two exclusion" paternity rule that evidentially states to exclude paternity only when more than two mismatches are observed at all tested loci. Y-STR and X-STR typing were also conducted separately to strengthen the paternity testing results. It underscores the need for further research and technological advancements to enhance our understanding of genetic mutations and improve the accuracy of paternity testing methodologies. Copyright@ International Science Community Association